548 Chas. W. Hargitt. 



after treatment with the chromic acid method suggested by 

 Browne, to the excellent results of which I am glad to certify. 



My thanks are due to my son, George T. Hargitt, who has 

 drawn most of the diagram sketches. 



AURELIA FLAVIDULA. 



The general facts of variation, or abnormality, as formerly 

 regarded, in species of Aurelia have long been known. It is no 

 part of the purpose of this paper to review in detail the history 

 of observations along this line, yet it may not be amiss to cite 

 some few of the more noteworthy among them. In a recent 

 paper, "Uber Hypomerie und Hypermerie bei Aurelia aurita 

 Lem.," Ballowitz has given a brief summary of the more impor- 

 tant literature. 



Von Baer^ seems to have been among the first to record obser- 

 vations upon the several numerical variations in Aurelia aurita, 

 and to point out certain correlations noticed, as well as their 

 absence in some cases. According to this author the variation 

 was estimated to be about 10 per cent. 



Of more critical character are the observations of Ehrenberg^ 

 in 1835. This naturalist in an extended paper "Uber die Acale- 

 phen des rothen Meeres, etc.," reports with considerable detail 

 upon variations observed in this medusa, and illustrates by 

 numerous figures the more conspicuous aspects of the problem. 

 He was able to confirm the earlier observations of von Baer, and 

 considerably to extend them. Among many thousands of 

 specimens casually noticed, and several hundreds examined 

 with care he records having seen but two specimens of octamerous 

 division of the gonads and comparatively few having a three-, 

 five- and six-merous character. He records a single specimen 

 observed with but one circular gonad about the mouth, which 

 he considered to have been the result of a fusion of three or six 

 single organs, as there were several openings into the stomach. 

 In a case having double gonads he considered the condition to be 

 due to a similar fusion of six organs as there were six openings 

 distinguished. Like von Baer, this observer also recognized a 



'Uber MeJusa aurita, Meckels Archiv. f. Physiol., Bd. viii, 1823. 

 ^Abhandl. d. Konigl. Akad. Wissenschaften, Berlin, 1835, S. 199-204, 1837. 



